Sayyiduna Abdullah bin Abbas (may Allah be pleased with them) narrates this statement of the Noble Prophet (peace and blessings be upon him): "If people were given (things) on the basis of their claims, then people would begin to make claims against the lives and properties of others. Therefore, it is obligatory upon the one against whom a claim is made to take an oath."
Hadith Referenceصحیح ابن حبان / كتاب الدعوى / 5083
Hadith Gradingفضيلة الشيخ الإمام محمد ناصر الدين الألبانيصحيح - المصدر نفسه: ق.فضيلة الشيخ العلّامة شُعيب الأرناؤوطإسناده صحيح